This invention relates to cotton fiber processing and more particularly to an apparatus and method of separating foreign matter from fibrous cotton that has been ginned from the seed. About 60 years ago cotton “lint Cleaners” were introduced into cotton gins in the United States to overcome the dramatic increase of extraneous matter brought to the gins in the seed cotton harvested by the newly introduced mechanical cotton harvesters as compared to the previously customary hand picked (harvested) cotton. These “Saw-type” lint cleaners did indeed greatly improve the appearance of the lint by removing much “trash”, but also by aggressively “combing” the tufts of fibers to diffuse them and hide the remaining fine trash particles. The most successful of these “Saw Type” lint cleaners contained a “Feed Roller” working against a concave “Feed Plate” to compact the lint batt and firmly hold it about 7 mm from the sharp tips of the fine teeth on the lint cleaner cleaning cylinder that plucked the fibers from the batt. These lint cleaners were commercially very successful because they made the lint appear to the naked eye to meet the higher grades in the classing sample standard grade boxes which were the primary determinant of the lint value along with the manually determined “staple length” which also “pulled” somewhat longer by the manual grading or classing systems of the day. Soon two and even three stages of these aggressive lint cleaners were used in series benefitting the farmers, but the results at the textile spinning mills proved disappointing.
The inadequacy of the manual-visual method of classing lint cotton became apparent, and innovative researchers introduced various cotton quality test instruments that measured spinning qualities that were only vaguely sensed by manual methods, if detected at all. Several of these test instruments were improved to perform fast enough to process lint samples as they were produced during the peak of the ginning season, and they were combined into a classing system referred to as “High Volume Instrumentation” (HVI). HVI systems were officially adopted for commerce in the United States and today HVI systems are being promoted for use around the world. However, there is much inertia in the long standing manual classing systems and the transition to HVI commercial use in many foreign countries may be very gradual.
As more of these accurate spinning quality tests were made using instrument testing equipment comparing the before and after lint quality through these saw type lint cleaners, it became clear that these lint cleaners were breaking many fibers and producing neps, both of which are very detrimental to yarn quality. The location within these saw type lint cleaners that caused this fiber quality damage was controversial, but it has now been shown that the major damage is caused at the point where the cotton batt is fed to the teeth of the cleaning cylinder.
Patent application Ser. No. 12/168,497 describes apparatus that reduces fiber damage by eliminating the formation of the cotton tufts into a batt, but rather, individually applies the tufts of cotton as they come from the gin stand in an air stream directly onto the teeth of the lint cleaner cleaning cylinder teeth without mechanically restraining the tufts. This patent application is for use with lint cleaners that have short, densely spaced teeth on a solid cylinder which currently are universally used in the U.S. saw gins on upland cotton.
Roller ginning in the United States has been almost entirely confined to ginning pima cotton which is more valuable than upland cottons because of its extra long, fine fibers that warrant the slow, more expensive roller ginning process that also breaks fewer fibers than saw ginning. However, the roller ginning process has recently been made much faster until roller ginning speed (Capacity) is now nearing saw ginning capacity per unit width of ginning machine. High speed roller ginning is now being introduced to the ginning of some upland cottons in response to monetary incentives for roller ginned lint. Roller ginned lint is classed on a different system from saw ginned lint. The roller ginned lint classing system has completely different standards for “preparation”. The roller ginned “prep” standard calls for a certain lumpy appearance caused by the roller gin that pulls off much larger tufts from the seed than saw gins. The lint cleaners used with roller gins, therefore, do not as aggressively “comb” the lint to preserve the characteristic lumpy appearance of roller ginned lint. The cleaning cylinders used on roller ginned cotton generally have less densely spaced teeth or even bars or lugs which would not provide an air seal between the cleaning cylinder and the high speed separator cylinder housing as is required in application Ser. No. 12/168,497. Furthermore, the textile industry, over many years has developed several specialized cotton cleaning cylinders, including “Kirschner” and “Buckley” beaters, which have more open designs that would allow air to be drawn through the cleaning cylinder back into the high speed separator housing if the apparatus of Ser. No. 12/168,497 were used. Moreover, the open design cleaning cylinders often are self doffing and therefore they eliminate the doffing cylinder of '497, a considerable initial and maintenance expense. The principle proven benefits of Ser. No. 12/168,497 would be lost for use with these many “open” cleaning cylinders without the added concepts of the present invention.
Other prior methods and apparatus include those such as illustrated in U.S. Pat. No. 6,088,881, incorporated herein by reference, wherein a revolving perforated drum is used to allow air flow through the drum such that a cleaning cylinder may remove cotton fiber from the perforated drum and carry it past a plurality of cleaning grid bars, thereby separating the air flow and removing foreign matter from the fibers, before the fiber is doffed from the cleaning cylinder for subsequent air flow to downstream processing.
However, the perforated revolving cylinder of the '881 apparatus, revolving at velocities to prevent agglomeration of the tufts in the air stream, develops centrifugal forces that cause the fine trash and very short fibers that penetrate the perforations to accumulate on the interior surfaces of the perforated cylinder. These accumulations require the use of compressed air blasts to cause them to move axially out the open ends of the cylinder. While the compressed air blasts provide a solution to this problem of accumulations, the maintenance and cost of the compressed air system detracts from the otherwise excellent performance of the apparatus per the '881 patent.
The quality preserving actions of the methods and apparatus shown in U.S. Pat. No. 6,088,881 and application Ser. No. 12/168,497 would be beneficial for use with all types of lint cleaning cylinders, including those used with roller gins. The improvement described herein provides the solution to combining the benefits of these concepts with cleaning cylinders of most all designs.